Position detection device, display device, method of controlling position detection device, and method of controlling display device

ABSTRACT

A position detection device includes a detection section adapted to detect an operation to a screen, a detection control section adapted to identify the pointing element with which the operation is performed, and associate the operation with the pointing element, and a processing section adapted to process the operation associated with the pointing element out of the operations. In the case in which a first operation and a second operation, which is performed within a predetermined period of time before the first operation, with a single pointing element are detected, and a coordinate of the first operation and a coordinate of the second operation are located within a predetermined range, the detection control section treats the coordinate of the first operation as the same coordinate as the coordinate of the second operation. Further, the detection control section changes the predetermined range in accordance with the detection position in the screen.

The entire disclosure of Japanese Patent Application No. 2015-059370,filed Mar. 23, 2015 is expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to a position detection device, a displaydevice, a method of controlling a position detection device, and amethod of controlling a display device.

2. Related Art

In the past, there has been known a position detection device fordetecting an operation to a display surface (see, e.g., JP-A-2011-203816(Document 1)). The coordinate input device of Document 1 is a coordinateinput device for detecting operation input to the operation screen, andcorrects the coordinate so that a single click operation or a doubleclick operation is easy to recognize even if wobbling of a motion of ahand of a human or a displacement of the input due to parallax or ashadow occurs when performing the click operation or the double clickoperation using an electronic pen, a hand, or the like.

However, in pointing an operation to the display surface using apointing element, it is not necessarily possible for the operator topoint the position, which the operator wants to point, without fail. Forexample, in the case of operating the pointing element standing up, ifthe operator is not used to the operation with the pointing element, thearm of the operator is not fixed when performing the operation, andtherefore, it is difficult to point the target position. Further, in thecase of the configuration in which the pointed position on the displaysurface pointed by the pointing element is detected by a detectionsection, the error included in the pointed position detected by thedetection section differs by the pointed position on the display surfacethus pointed in some cases, and therefore, it is difficult to accuratelydetect the position pointed by the pointing element.

SUMMARY

An advantage of some aspects of the invention is to provide a positiondetection device, a display device, a method of controlling a positiondetection device, and a method of controlling a display device eachimproved in operability of the operation with a pointing element.

A position detection device according to an aspect of the inventionincludes a detection section adapted to detect an operation to a displaysurface, an identification section adapted to identify a pointingelement with which the operation detected by the detection section isperformed, and associate the operation and the pointing element witheach other, and a processing section adapted to process the operationassociated with the pointing element out of the operations detected bythe detection section, and in a case in which a first operation and asecond operation, which is performed within a predetermined period oftime before the first operation, with a single pointing element aredetected, and a coordinate of the first operation and a coordinate ofthe second operation are located within a predetermined range, theidentification section treats the coordinate of the first operation asthe same coordinate as the coordinate of the second operation, and theidentification section changes a predetermined range in accordance witha detection position in the display surface of the operation detected bythe detection section.

According to this aspect of the invention, it is possible to improve theoperability of the operation with the pointing element.

According to another aspect of the invention, in the position detectiondevice described above, the identification section determines whether ornot the coordinate of the first operation is treated as the samecoordinate as the coordinate of the second operation in accordance withconfiguration information set so that the range set to a first positionin the display surface is larger than the range set to a second positionlocated above the first position.

According to this aspect of the invention, in the lower part of thedisplay surface, it is possible to increase the possibility that thecoordinates pointed with the pointing element are determined as the samecoordinate despite the variation.

According to another aspect of the invention, in the position detectiondevice described above, the identification section determines whether ornot the coordinate of the first operation is treated as the samecoordinate as the coordinate of the second operation in accordance withconfiguration information set so that the range set to a first positionin the display surface is larger than the range set to a second positionlocated closer to the detection section than the first position.

According to this aspect of the invention, even in the case in which thepositions distant from the detection section are pointed with thepointing element, and there is a variation in the coordinates thuspointed, it is possible to increase the possibility that the coordinatesare determined as the same coordinate.

According to another aspect of the invention, in the position detectiondevice described above, there is further included an emission sectioninstalled in a top part of the display surface, and adapted to emitdetection light used to detect the pointing element, and the detectionsection is installed in the top part of the display surface, and shootsthe detection light reflected by the pointing element, with which theoperation to the display surface is performed, to detect the operationto the display surface with the pointing element.

A display device according to still another aspect of the inventionincludes a display section adapted to display an image on a displaysurface, a detection section adapted to detect an operation to thedisplay surface, an identification section adapted to identify apointing element with which the operation detected by the detectionsection is performed, and associate the operation and the pointingelement with each other, and a processing section adapted to process theoperation associated with the pointing element out of the operationsdetected by the detection section, and in a case in which a firstoperation and a second operation, which is performed within apredetermined period of time before the first operation, with a singlepointing element are detected, and a coordinate of the first operationand a coordinate of the second operation are located within apredetermined range, the identification section treats the coordinate ofthe first operation as the same coordinate as the coordinate of thesecond operation, and the identification section changes a predeterminedrange in accordance with a detection position in the display surface ofthe operation detected by the detection section.

According to this aspect of the invention, it is possible to improve theoperability of the operation with the pointing element.

A method of controlling a position detection device according to yetanother aspect of the invention includes detecting an operation to adisplay surface, identifying a pointing element with which the operationdetected in the detecting is performed, and associating the operationand the pointing element with each other, and processing the operationassociated with the pointing element out of the operations detected inthe detecting, and, in a case in which a first operation and a secondoperation, which is performed within a predetermined period of timebefore the first operation, with a single pointing element are detected,and a coordinate of the first operation and a coordinate of the secondoperation are located within a predetermined range, the coordinate ofthe first operation is treated as the same coordinate as the coordinateof the second operation in the identifying, and a predetermined range ischanged in accordance with a detection position in the display surfaceof the operation detected in the detecting.

According to this aspect of the invention, it is possible to improve theoperability of the operation with the pointing element.

A method of controlling a display device according to still yet anotheraspect of the invention includes displaying an image on a displaysurface, detecting an operation to the display surface, identifying apointing element with which the operation detected in the detecting isperformed, and associating the operation and the pointing element witheach other, and processing the operation associated with the pointingelement out of the operations detected in the detecting, and, in a casein which a first operation and a second operation, which is performedwithin a predetermined period of time before the first operation, with asingle pointing element are detected, and a coordinate of the firstoperation and a coordinate of the second operation are located within apredetermined range, the coordinate of the first operation is treated asthe same coordinate as the coordinate of the second operation in theassociating, and a predetermined range is changed in accordance with adetection position in the display surface of the operation detected inthe detecting.

According to this aspect of the invention, it is possible to improve theoperability of the operation with the pointing element.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic configuration diagram of a projection system.

FIG. 2 is a functional block diagram of the projection system.

FIG. 3 is a diagram showing a communication sequence of a projector, afirst pointing element, and a light emitting device.

FIG. 4 is a flowchart showing a process of a control section.

FIG. 5 is a diagram showing a state of detecting a pointed position by asecond pointing element.

FIG. 6 is a diagram showing a state of detecting a pointed position bythe second pointing element.

DESCRIPTION OF EXEMPLARY EMBODIMENTS First Embodiment

An embodiment of the invention will hereinafter be described withreference to the accompanying drawings.

FIG. 1 is a diagram showing a configuration of a projection system 1according to the embodiment to which the invention is applied. Theprojection system 1 is provided with a projector 10 disposed above ascreen SC (display surface), and a light emitting device 100 installedin a top part of the screen SC.

The projector 10 is disposed directly above or obliquely above thescreen SC, and projects an image toward the screen SC located obliquelybelow. Further, the screen SC illustrated in the present embodiment is aflat plate or a curtain fixed to a wall surface, or erected on the floorsurface. Further, the display surface is not limited to the screen SC,and it is also possible to use the wall surface as the screen SC. Inthis case, it is preferable to attach the projector 10 and the lightemitting device 100 to an upper part of the wall surface used as thescreen SC.

The projection system 1 detects an operation of the operator to thescreen SC. In the operation to the screen SC, there can be used a firstpointing element 70 having a pen-like shape or a second pointing element80 as a hand finger of the operator. The first pointing element 70 isoperated so that a tip portion 71 has contact with the screen SC with asleeve section 72 having a rod-like shape held by the operator in hand.

FIG. 2 is a functional block diagram of a variety of sectionsconstituting the projection system 1. Firstly, a configuration of thefirst pointing element 70 will be described.

The first pointing element 70 is provided with a control section 73, atransmitting/receiving section 74, an operation switch 75, and a powersupply section 76. The control section 73, the transmitting/receivingsection 74 and the power supply section 76 are housed in the sleevesection 72.

The transmitting/receiving section 74 is provided with a light sourcesuch as an infrared LED, and a light receiving element for receivinginfrared light (an infrared signal), puts ON/OFF the light source inaccordance with control by the control section 73, and outputs a signalrepresenting the light reception state of the light receiving element tothe control section 73.

The operation switch 75 is incorporated in the tip portion 71 of thefirst pointing element 70, and turns ON in the case in which the tipportion 71 of the first pointing element 70 has contact with the wall orthe screen SC to thereby be pressed.

The control section 73 is connected to the transmitting/receivingsection 74 and the operation switch 75, and detects one of an ON stateand an OFF state of the operation switch 75. The control section 73makes a lighting pattern of the light source provided to thetransmitting/receiving section 74 different between the case in whichthe operation switch 75 is in the ON state and the case in which theoperation switch 75 is in the OFF state. The projector 10 detects theposition of the tip portion 71 based on the infrared light (the infraredsignal) emitted by the first pointing element 70. Further, the projector10 determines whether or not the first pointing element 70 is pressedagainst the wall or the screen SC based on the lighting pattern of theinfrared light emitted by the first pointing element 70.

The power supply section 76 has a dry battery or a secondary cell as apower source, and supplies the electric power to each of the sections,namely the control section 73, the transmitting/receiving section 74,and the operation switch 75. The first pointing element 70 is providedwith a power switch (not shown) for switching ON/OFF the power supplyfrom the power supply section 76.

Then, a configuration of the projector 10 will be described.

The projector 10 is connected to an image supply device (not shown) suchas a personal computer (PC), a video reproduction device, a DVDreproduction device, or a Blu-ray (registered trademark) discreproduction device. The projector 10 projects an image on the screen SCbased on an analog image signal or digital image data supplied from theimage supply device. Further, it is also possible for the projector 10to read out the image data stored in a storage section 60 incorporatedin the projector 10 or a storage medium externally connected to theprojector 10, and then display an image on the screen SC based on theimage data.

The projector 10 is provided with an I/F (interface) section 11 and animage I/F (interface) section 12 as interfaces to be connected toexternal devices. It is also possible for the I/F section 11 and theimage I/F section 12 to be provided with connecters for wiredconnection, and each provided with an interface circuit compatible withthe connector described above. Further, the I/F section 11 and the imageI/F section 12 each can also be provided with a wireless communicationinterface. As the connector and the interface circuit for the wiredconnection, there can be cited those compliant to wired LAN, IEEE1394,USB, or the like. Further, as the wireless interface, there can be citedthose compliant to wireless LAN, Bluetooth (registered trademark), orthe like. As the image I/F section 12, there can also be used aninterface for image data such as an HDMI (registered trademark)interface. The image I/F section 12 can also be provided with aninterface through which sound data is input.

The I/F section 11 is an interface for transmitting and receiving avariety of types of data with an external device such as a PC. The I/Fsection 11 inputs and outputs control data related to projection of animage, configuration data for setting the operation of the projector 10,a coordinate of a pointed position detected by the projector 10, and soon. The control section 30 described later transmits and receives datawith an external device via the I/F section 11.

The image I/F section 12 is an interface through which the digital imagedata is input. The projector 10 according to the present embodimentprojects an image based on the digital image data input via the imageI/F section 12. It should be noted that the projector 10 can also beprovided with a function of projecting an image based on the analogimage signal, and in this case, the image I/F section 12 can be providedwith an interface for an analog image signal, and an A/D conversioncircuit for converting the analog image signal into digital image data.

The projector 10 is provided with a projection section 20 for performingformation of an optical image. The projection section 20 is providedwith a light source section 21, a light modulation device 22, and aprojection optical system 23. The light source section 21 is providedwith a light source formed of a xenon lamp, a super-high pressuremercury lamp, a light emitting diode (LED), a laser source, or the like.Further, the light source section 21 can also be provided with areflector and an auxiliary reflector for guiding the light emitted bythe light source to the light modulation device 22. Further, a lensgroup (not shown) for enhancing the optical characteristics of theprojection light, a polarization plate, a dimming element for reducingthe light intensity of the light emitted by the light source on a pathleading to the light modulation device 22, and so on can also beprovided.

The light modulation device 22 is provided with, for example, threetransmissive liquid crystal panels corresponding respectively to thethree primary colors of RGB, and modulates the light to be transmittedthrough the liquid crystal panels to thereby generate the image light.The light from the light source section 21 is separated into coloredlight beams of three colors of RGB, and the colored light beams enterthe corresponding liquid crystal panels, respectively. The colored lightbeams, which have been modulated while passing through the respectiveliquid crystal panels, are combined by a combining optical system suchas a cross dichroic prism, and are then output to the projection opticalsystem 23.

The projection optical system 23 is provided with a lens group forguiding the image light, which has been modulated by the lightmodulation section 22, toward the screen SC to form the image on thescreen SC. Further, the projection optical system 23 can also beprovided with a zoom mechanism for performing expansion/contraction ofthe projection image on the screen SC, and a focus adjustment mechanismfor performing an adjustment of the focus. In the case in which theprojector 10 is of a short focus type, it is also possible to providethe projection optical system 23 with a concave mirror for reflectingthe image light toward the screen SC.

To the projection section 20, there are connected a light source drivesection 45 for lighting the light source section 21 in accordance withthe control by the control section 30, and a light modulation devicedrive section 46 for operating the light modulation device 22 inaccordance with the control by the control section 30. The light sourcedrive section 45 can also be provided with a function of switchingbetween lighting and extinction of the light source section 21 tocontrol the light intensity of the light source section 21.

The projector 10 is provided with an image processing system forprocessing the image to be projected by the projection section 20. Theimage processing system includes the control section 30 for controllingthe projector 30, the storage section 60, an image processing section40, and a frame memory 41. The projector 10 is provided with anoperation panel 17, an operation detection section 18, a remote controlreceiver 19, a detection section 50, an attitude sensor 47, an emissiondevice drive section 48, a connection section 49. The control section 30and the detection section 50 constitute a position detection device 65.

The control section 30 is provided with hardware such as a CPU, a ROM,and a RAM, and controls the projector 10 by the CPU executing a basiccontrol program stored in the ROM and a control program stored in thestorage section 60. Further, the control section 30 executes the controlprogram stored in the storage section 60 to thereby function as aprojection control section 31, an emission control section 32, acalibration control section 33, a detection control section (anidentification section) 34, and a processing section 35. The detailedexplanation of each of the functional blocks will be described later.

The storage section 60 is a nonvolatile memory such as a flash memory oran EEPROM, and stores the control program and configuration information61 used by the control section 30 for the control. The configurationinformation 61 includes threshold values used in the processing by thecontrol section 30. The threshold values are each a threshold value forthe distance used to determine whether or not coordinates of twodifferent points on the screen SC pointed by a single first pointingelement 70 are treated as the same coordinates. The storage section 60stores two threshold values, namely a threshold value for an upper partand a threshold value for a lower part. The threshold value for theupper part is the threshold value used in the case in which the firstpointing element 70 points an upper area (a second position) in the caseof dividing the screen SC into two areas in the middle in the verticaldirection. Further, the threshold value for the lower part is athreshold value used in the case in which a lower area (a firstposition) of the screen SC is indicated by the first pointing element70. The threshold value for the lower part is set to a higher value thanthe threshold value for the upper part.

It should be noted that the threshold values used for the determinationare not limited to the two values respectively for the upper part andthe lower part. For example, it is also possible to divide the screen SCinto three areas, namely an upper part, a lower part, and a middle part,and use the threshold values corresponding to the respective areas.Further, it is also possible to arrange that the threshold valueincreases in the direction from the upper area to the lower area of thescreen SC. Further, in the case in which the projector 10 including thedetection section 50 and the light emitting device 100 are located inthe lower part of the screen SC, it is also possible to arrange that thethreshold value corresponding to the upper area of the screen SC ishigher than the threshold value corresponding to the lower area. Inother words, in the case in which the detection section 50 and the lightemitting device 100 are located in a first direction side with respectto the screen SC (e.g., the detection section 50 and the light emittingdevice 100 are both located in the upper part, or located in the lowerpart), it is also possible to set the threshold value corresponding tothe second area of the screen SC located on the opposite side to thefirst direction side with respect to the first area to be higher thanthe threshold value corresponding to the first area.

The image processing section 40 obtains the image data input through theimage I/F section 12 in accordance with the control by the controlsection 30 to determine an attribute such as the image size, theresolution, whether the image is a still image or a moving image, theframe rate in the case in which the image is a moving image, and whetheror not the image data is 3D image data, with respect to the image datathus obtained.

The image processing section 40 is connected to the frame memory 41, anddevelops the image data thus obtained in the frame memory 41 frame byframe. The image processing section 40 performs the image processing onthe image data thus developed. The image processing section 40 performsa process such as a resolution conversion process, a gamma correctionprocess, a color shading correction process, a luminance correctionprocess, or a shape correction process as the image processing. Further,it is obviously possible for the image processing section 40 to performtwo or more of the processes described above in combination with eachother.

The image processing section 40 reads out the image having beenprocessed from the frame memory 41, generates image signals of R, G, andB corresponding to the image, and then outputs the image signals to thelight modulation device drive section 46.

The light modulation device drive section 46 drives the liquid crystalpanels of the light modulation device 22 based on the image signal inputfrom the image processing section 40 to draw the image.

The operation panel 17 is provided with a variety of switches andindicator lamps for the operator to perform operations. The operationpanel 17 is connected to the operation detection section 18. Theoperation detection section 18 appropriately lights or blinks theindicator lamps of the operation panel 17 in accordance with theoperation state and the setting state of the projector 10 in accordancewith the control by the control section 30. When the switch of theoperation panel 17 is operated, an operation signal corresponding to theswitch having been operated is input to the control section 30 via theoperation detection section 18.

Further, the remote control receiver 19 receives the infrared signalemitted by the remote controller (not shown). The remote controlreceiver 19 is connected to the operation detection section 18. Theremote control receiver 19 decodes the infrared signal received from theremote controller to generate an operation signal representing theoperation content in the remote controller, and then outputs theoperation signal to the operation detection section 18. The operationsignal generated by the remote control receiver 19 is input to thecontrol section 30 via the operation detection section 18.

The emission device drive section 48 is connected to the light emittingdevice 100 via the connection section 49. The connection section 49 is,for example, a connector having a plurality of pins, and the lightemitting device 100 is connected to the connection section 49 via acable 110. The emission device drive section 48 generates a pulse signalin accordance with the control by the control section 30, and thenoutputs the pulse signal to the light emitting device 100 via theconnection section 49. Further, the emission device drive section 48supplies the light emitting device 100 with the electric power via theconnection section 49.

As shown in FIG. 1, the light emitting device 100 is configured housinga light source section 101 and optical components in a case having aroughly box-like shape. In the light emitting device 100 according tothe present embodiment, the light source section 101 is provided with asolid-state light source (not shown) for emitting the infrared light.The infrared light emitted by the solid-state light source is diffusedby a collimating lens and a Powell lens to form a plane along the screenSC. Further, it is also possible to arrange that the light sourcesection 101 is provided with a plurality of solid-state light sources,and the light emitted by each of the solid-state light sources isdiffused to thereby form the layer of light so as to cover an imageprojection range of the screen SC. Further, it is also possible for thelight emitting device 100 to be provided with an adjustment mechanismfor adjusting a distance and an angle between the layer of the lightemitted by the light source section 101 and the screen SC.

The light emitting device 100 lights the light source section 101 usingthe pulse signal and the electric power supplied from the emissiondevice drive section 48. The timing at which the light source section101 is put ON or OFF is controlled by the emission device drive section48. The control section 30 controls the emission device drive section 48to light the light source section 101 in sync with the timing at which ashooting section 51 described later performs shooting.

The detection section 50 is provided with the shooting section 51, ashooting control section 52, a transmitting section 53, a positiondetection section 54, and a coordinate detection section 55, and detectsthe operation of the first pointing element 70 and the second pointingelement 80 to the screen SC.

The shooting section 51 is incorporated in the projector 10 disposedabove the screen SC. The shooting section 51 has an imaging opticalsystem, an imaging element, an interface circuit, and so on, and shootsthe projection direction of the projection optical system 23. Theimaging optical system of the shooting section 51 is disposed facing toroughly the same direction as the projection optical system 23, and hasa field angle of defining a range including the screen SC and theperiphery of the screen SC as a shooting range. Further, as the imagingelement, there can be cited a CCD and a CMOS capable of receiving lightin the infrared region and the visible region. The shooting section 51can also be provided with a filter partially blocking the light enteringthe imaging element, and in the case where the infrared light isreceived, it is also possible to dispose a filter for mainlytransmitting the light in the infrared region in front of the imagingelement, for example. Further, the interface circuit of the shootingsection 51 reads out and then outputs the detection value of the imagingelement.

The shooting control section 52 makes the shooting section 51 performshooting to form data of the shot image. When the imaging elementperforms shooting with visible light, the image projected on the screenSC is shot. Further, the shooting control section 52 can make theshooting section 51 shoot the infrared light, and in the data of theshot image on this occasion, there appear the infrared light (theinfrared signal) emitted by the first pointing element 70, and thereflected light (detection light) which is the infrared light havingbeen emitted by the light emitting device 100 and then reflected by thesecond pointing element 80.

The transmitting section 53 transmits the infrared signal to the firstpointing element 70 in accordance with the control by the shootingcontrol section 52. The transmitting section 53 has a light source suchas an infrared LED, and puts ON or OFF the light source in accordancewith the control by the position detection section 54.

The position detection section 54 detects the image of the light emittedby the first pointing element 70, and the image of the reflected lightreflected by the second pointing element 80 from the data of the shotimage input from the shooting control section 52. The position detectionsection 54 detects the image of the light from the data of the shotimage shot in second through fourth phases described later.

The coordinate detection section 55 detects the coordinate of theposition of the image of the light in the data of the shot image basedon the position of the image of the light detected by the positiondetection section 54 from the data of the shot image in the secondthrough fourth phases. Further, it is also possible for the coordinatedetection section 55 to calculate the coordinates of the pointedpositions by the pointing elements 70, 80 in the projection imageprojected by the projection section 20 to output the result to thecontrol section 30. Further, it is also possible for the coordinatedetection section 55 to calculate the coordinates of the pointedpositions by the pointing elements 70, 80 in the image data drawn by theimage processing section 40 in the frame memory 41, and the coordinatesof the pointed positions by the pointing elements 70, 80 in the inputimage data of the image I/F section 12.

FIG. 3 is a diagram showing a communication sequence of the projector10, the first pointing element 70, and the light emitting device 100.The projector 10 repeatedly performs the communication sequenceincluding four phases, namely first through fourth phases, to performcommunication with the first pointing element 70 and the light emittingdevice 100. The lengths of the respective phases are set to the sameperiods. Further, although the light emitting time of a single lightemission operation of the transmitting section 53 is set to be onefourth of a single phase, the light emitting time of a single lightemission operation of the first pointing element 70 is set to be oneeighth of a single phase, and the light emitting time of a single lightemission operation of the light emitting device 100 is set to be asingle phase, these are illustrative only.

The first phase is a phase for synchronizing the first pointing element70 with the projector 10. In the first phase, the transmitting section53 of the projector 10 emits light to transmit the infrared signal forsynchronization. The control section 73 of the first pointing element 70detects the infrared signal for the synchronization in thetransmitting/receiving section 74 to recognize start timing of the firstphase.

The second phase is a phase for the position detection, and the lightsource section 101 of the light emitting device 100 and thetransmitting/receiving section 74 of the first pointing element 70 areput ON. The projector 10 shoots the shooting range using the shootingsection 51 in sync with the light emission timing of the light emittingdevice 100 and the first pointing element 70. For example, if theshooting section 51 performs shooting in the second phase, the lightemitted by the first pointing element 70, and the reflected lightreflected by the second pointing element 80 appear in the data of theshot image.

The shooting timing and the shooting intervals of the shooting section51 are set in advance, and the number of times of shooting per phase canbe one or more than one. In the case in which the first pointing element70 emits light once a phase as shown in FIG. 3, it is desirable toperform shooting at at least the timing when the first pointing element70 emits light in each phase. Further, a method of adjusting theshooting timing of the shooting section 51 and the light emission timingof each of the sections is arbitrary. Since it is generally difficult tomake the shooting timing and the shooting intervals of the shootingsection 51 variable inmost cases, it is advisable to adjust the lightemission timing of the transmitting section 53 taking the shootingtiming of the shooting section 51 into consideration.

The third phase is a phase for determining the pointing element. In thethird phase, the first pointing element 70 emits light, while the lightemitting device 100 does not emit light. Therefore, in the data of theshot image shot by the shooting section 51 in the third phase, the imageof the light emitted by the first pointing element 70 appears, and thereflected light by the second pointing element 80 does not appear.

The four phase is a phase for the position detection similarly to thesecond phase, and the light source section 101 of the light emittingdevice 100 and the transmitting/receiving section 74 of the firstpointing element 70 are put ON.

It is possible for the control section 30 of the projector 10 to tellwhether the image of the light appears in the data of the shot images inthe second and fourth phases is the image of the light of the firstpointing element 70 or the image of the reflected light of the secondpointing element 80 by comparing the data of the shot image in the thirdphase and the data of the shot images in the second and fourth phaseswith each other. Further, in the case in which a plurality of images ofthe light appears in the data of the shot images, it is possible to tellwhich one of the images of the light is the image of the light of thefirst pointing element 70, and which one of the images of the light isthe image of the light of the second pointing element 80.

Further, in the case in which the period of each of the phases issufficiently short, the positions of the images appearing in the data ofthe shot images in the consecutive second, third, and fourth phasesbecome sufficiently close to each other. Therefore, it is easy to tellthe image of the light of the first pointing element 70 and the image ofthe reflected light of the second pointing element 80 from each other.

Further, in the case of performing an operation using a plurality offirst pointing elements 70, it is possible to identify the lightemission of each of the first pointing elements 70 in the data of theshot images of the shooting section 51.

Specifically, it is sufficient to set light emission timings differentfrom each other to the respective first pointing elements 70 in advance.

For example, in the case of assuming that the pointing elements used inthe operation are the first pointing element 70A and the first pointingelement 70B, lighting/non-lighting states in the third phase in fourconsecutive communication sequences are set in the first pointingelement 70A as “1001” (“1” denotes lighting state, and “0” denotesnon-lighting state). Further, the lighting/non-lighting states in thethird phase in four consecutive communication sequences are set in thefirst pointing element 70B as “0101.” In this case, the control section30 can distinguish the first pointing element 70A and the first pointingelement 703 from each other by comparing the images of the lightappearing in the data of the shot images shot in the third phase of thefour consecutive communication sequences with each other.

The attitude sensor 47 is formed of an acceleration sensor, a gyrosensor, or the like, and outputs the detection value to the controlsection 30. The attitude sensor 47 is fixed to the main body of theprojector 10 so as to be able to identify the installation direction ofthe projector 10.

The projector 10 can be used in an installation condition for performingprojection from below the screen SC, an installation condition for usinga horizontal surface such as atop surface of a desk as the screen SC,and soon in addition to the suspended installation of being suspendedfrom the wall surface or the ceiling surface shown in FIG. 1. Someinstallation conditions of the projector 10 are not appropriate for theuse of the light emitting device 100. For example, in the case in whichthe projector 10 and the light emitting device 100 are installed belowthe screen SC to perform the projection from below the screen SC, thebody of the operator blocks the light emitted from the light emittingdevice 100 in some cases, which is not appropriate. The attitude sensor47 is provided to the main body of the projector 10 so as to be able toidentify the plurality of installation conditions assumed as theinstallation condition of the projector 10. The attitude sensor 47 isconfigured using, for example, a dual-axis gyro sensor, a single-axisgyro sensor, or an acceleration sensor. The control section 30 canautomatically determine the installation condition of the projector 10based on the output value of the attitude sensor 47. In the case inwhich the control section 30 has determined that the installationcondition is inappropriate for the use of the light emitting device 100,it is also possible to arrange that, for example, the emission devicedrive section 48 stops outputting the power supply voltage and the pulsesignal.

Then, a process of each of the functional blocks provided to the controlsection 30 will be described.

The projection control section 31 obtains the content of the operationhaving been performed by the operator based on the operation data inputfrom the operation detection section 18. The projection control section31 controls the image processing section 40, the light source drivesection 45, and the light modulation device drive section 4G inaccordance with the operation performed by the operator to project theimage on the screen SC.

Further, the projection control section 31 controls the image processingsection 40 to perform a discrimination process between a 3D(stereoscopic) image and a 2D (planar) image described above, aresolution conversion process, a frame rate conversion process, adistortion correction process, a digital zoom process, a colorcorrection process, a luminance correction process, and so on.

Further, the projection control section 31 controls the light sourcedrive section 45 in accordance with the process of the image processingsection 40 to thereby control the light intensity of the light sourcesection 21.

The emission control section 32 controls the emission device drivesection 48 to execute or stop output of the electric power and the pulsesignal to the light emitting device 100 connected to the connectionsection 49. In the case in which the light emitting device 100 cannot beused or is not used, the emission control section 32 makes the emissiondevice drive section 48 stop outputting the electric power and the pulsesignal. Further, in the case of using the light emitting device 100, theemission control section 32 makes the emission device drive section 48output the electric power and the pulse signal.

The calibration control section 33 performs the calibration. Thecalibration is a process for achieving association in position betweenthe projection image projected on the screen SC and the data of the shotimage shot by the shooting section 51. The calibration control section33 performs, for example, an automatic calibration as a calibrationrelated to the pointed position by the pointing element 70 or thepointing element 80. The automatic calibration is a process ofprojecting an image for the automatic calibration on the screen SC,shooting the shooting range including the screen SC with the shootingsection 51, and then generating calibration data using the data of theshot image of the shooting section 51. In the image for the automaticcalibration, there is displayed a plurality of marks. The calibrationcontrol section 33 associates the marks detected from the data of theshot image and the projection image drawn in the frame memory 41, namelythe marks in the automatic calibration image, with each other togenerate the calibration data.

Further, the calibration control section 33 can also perform a manualcalibration instead of, or together with, the automatic calibration. Inthe case of performing the manual calibration, the calibration controlsection 33 projects an image for the manual calibration on the screenSC. In the image for the manual calibration, there is also displayed aplurality of marks. In the manual calibration, the operator points eachof the marks in the image for the manual calibration displayed on thescreen SC with the first pointing element 70 or the second pointingelement 80. The calibration control section 33 detects the operation bythe pointing element 70 or the pointing element 80 to the image thusprojected from the data of the shot image shot by the shooting section51 to generate the calibration data.

The detection control section 34 controls the detection section 50 todetect the operation (the coordinate of the pointed position) to thescreen SC by the first pointing element 70 or the second pointingelement 80.

Further, the detection control section 34 determines whether the brightpoint appears in the data of the shot image is the image of the lightemitted by the first pointing element 70 or the image of the reflectedlight reflected by the second pointing element 80 based on the data ofthe shot images shot in the second, third, and fourth phases.Specifically, the detection control section 34 determines that thebright points, which are detected in the data of the shot images in allof the second, third, and fourth phases, and located at roughly the samepositions, correspond to the pointed position by the first pointingelement 70. Further, the detection control section 34 determines thatthe bright points, which are detected in the data of the shot images inthe second and fourth phases, not detected in the data of the shot imagein the third phase, and located at roughly the same positions,correspond to the pointed position by the second pointing element 80.

It should be noted that in the case in which the shooting intervals ofthe shooting section 51 are extremely short, the image of the lightemitted by the first pointing element 70 and the image of the reflectedlight of the second pointing element 80 are detected at the sameposition in the data of the shot image shot in a single communicationsequence. However, since the detection positions of the bright pointsare shifted from each other in some cases depending on the shootingtiming, the coordinates of the bright points detected from the data ofthe shot image are not required to completely coincide with each other,but are only required to be roughly the same.

Further, the detection control section 34 determines whether or not thetip portion 71 of the first pointing element 70 has contact with thescreen SC based on the data of the shot image in the third phase. Forexample, it is also possible to determine whether the first pointingelement 70 and the screen SC are in the contact state or the noncontactstate by changing the lighting pattern of the first pointing element 70in the third phase. For example, it is also possible to divide thepointing element determination phase into four sections, and make thesection in which the transmitting/receiving section 74 of the firstpointing element 70 is put ON different between the case in which theoperation switch 75 is in the ON state and the case in which theoperation switch 75 is in the OFF state as shown in FIG. 3. For example,in the case in which the operation switch 75 is in the ON state, thetransmitting/receiving section 74 is lit in odd sections (the first andthird sections) out of the four sections, and in the case in which theoperation switch 75 is in the OFF state, the transmitting/receivingsection 74 of the first pointing element 70 is lit in even sections (thesecond and fourth sections) out of the four sections.

Further, when the detection control section 34 has determined that thecoordinate detected from the data of the shot image is the coordinate ofthe pointed position by the first pointing element 70, the detectioncontrol section 34 determines whether or not the coordinate thusdetected will be changed.

There is assumed the case of using the projection system 1 for, forexample, an elementary school class. In this case, elementary schoolstudents often have muscle weakness and are unfamiliar with the firstpointing element 70 having a pen-like shape. Therefore, in the case inwhich the student performs an operation such as drawing of charactersand figures on the screen SC or selection of buttons disposed in themenu bar projected on the screen SC using the first pointing element 70,there is a high possibility that the tip portion 71 of the firstpointing element 70 wobbles despite the intention. In other words, theprojector 10 detects a plurality of coordinates as the pointed positionsin a short period of time in some cases, which results in an unwantedoperation for the student.

Therefore, in the case in which a plurality of coordinates as thepointed positions by the first pointing element 70 have been detected ina predetermined period of time, the detection control section 34determines whether or not these coordinates are treated as the samecoordinate by comparing the distances between the coordinates with athreshold value.

Further, in the case of using the projection system 1 for, for example,an elementary school class, since the students are short in height andunable to reach the upper part of the screen SC, there can be assumedthe case in which the student uses the lower part of the screen SC andthe teacher uses the upper part of the screen SC. Therefore, thedetection control section 34 changes the threshold value used for thecomparison with the distance between the coordinates described abovebased on whether the coordinates detected are the coordinates located inthe upper part of the screen SC or the coordinates located in the lowerpart of the screen SC.

FIG. 4 is a flowchart showing a processing flow for determining whetheror not the coordinate of the pointed position will be changed. Thisprocessing flow will be described below with reference to FIG. 4.

When a coordinate (hereinafter referred to as a first coordinate) of abright point appearing in the data of the shot images in the secondphase and the fourth phase is input from the detection section 50 (YESin the step S1), the detection control section 34 determines (step S2)whether or not the pointing element pointing the first coordinate is thefirst pointing element 70. The first coordinate is a coordinate detectedfrom the data of the shot image obtained by shooting a first operation,which is performed by the operator on the screen SC, with the shootingsection 51. The determination method on whether or not the firstcoordinate is the coordinate pointed by the first pointing element 70 isas described above.

In the case in which a negative determination has been made in the stepS2, the detection control section 34 makes the transition to a processin the step S13. The process in the step S13 will be described later.

Further, in the case in which an affirmative determination has been madein the step S2, the detection control section 34 determines (step S3)whether or not there exists a coordinate (hereinafter referred to as asecond coordinate) having been pointed by the first pointing element 70within a predetermined time before pointing of the first coordinate. Thepredetermined time is set to an appropriate value taking practicaldetermination accuracy into consideration.

When the coordinate is input from the detection section 50, thedetection control section 34 stores the coordinate thus input and thepointing element 70 or 80 having pointed the coordinate in a memory suchas a RAM so as to be associated with each other. Further, the secondcoordinate is a coordinate detected from the data of the shot imageobtained by shooting a second operation, which is performed by theoperator on the screen SC, with the shooting section 51.

In the case in which a negative determination has been made in the stepS3, the detection control section 34 makes the transition to the processin the step S13. Further, in the case in which an affirmativedetermination has been made in the step S3, the detection controlsection 34 calculates (step S4) a distance between the first coordinateand the second coordinate.

Further, in the case in which a negative determination has been made inthe step 92, or a negative determination has been made in the step S3,the detection control section 34 makes the transition to the process inthe step S13. In the step S13, the detection control section 34determines whether or not the first coordinate has newly been input. Inthe case in which the new first coordinate has been input (YES in thestep S13), the detection control section 34 returns to the step S2 torepeat the processes from the step S2 once again. Further, in the casein which the new first coordinate has not been input (NO in the stepS13), the detection control section 34 terminates the processing flow.

The detection control section 34 calculates the distance between thecoordinates, namely the first coordinate and the second coordinate inthe step S4, and then converts (step S5) the first coordinate into acoordinate on the screen SC. The detection control section 34 calculatesthe data representing the range of the screen SC in the data of the shotimage based on the calibration data generated by the calibration controlsection 33. The detection control section converts the first coordinateinto the coordinate (hereinafter referred to as a third coordinate) onthe screen SC based on the data representing the range of the screen SC.The detection control section 34 determines (step S6) whether the thirdcoordinate obtained by the conversion is located in the upper part ofthe screen SC or located in the lower part of the screen SC. In thepresent embodiment, an upper area in the case of dividing the screen SCinto two areas in the middle in the vertical direction is referred to asthe upper part of the screen SC, and the lower area is referred to asthe lower part of the screen SC.

In the case in which the detection control section 34 has determinedthat the third coordinate is located in the upper part of the screen SC(YES in the step S6), the detection control section 34 reads out thethreshold value for the upper part of the screen SC from the storagesection 60 to compare (step S7) the threshold value with the distancebetween the coordinates calculated in the step S4. In the case in whichthe distance between the coordinates is shorter than the threshold valuefor the upper part (YES in the step S8), the detection control section34 changes the first coordinate to the second coordinate to treat (stepS11) the first coordinate as the same coordinate as the secondcoordinate. Specifically, the detection control section 34 determinesthat an erroneous coordinate has been detected as the pointed positiondue to the wobble of the tip portion 71 when operating the firstpointing element 70, and changes the first coordinate to the secondcoordinate. Further, in the case in which the distance between thecoordinates is equal to or longer than the threshold value for the upperpart (NO in the step S8), the detection control section 34 determines(step S12) the distance as a movement of the coordinate. In other words,the detection control section 34 determines that the pointed position bythe first pointing element 70 has been changed from the secondcoordinate to the first coordinate.

Further, in the case in which the detection control section 34 hasdetermined that the third coordinate is located in the lower part of thescreen SC (NO in the step S6), the detection control section 34 readsout the threshold value for the lower part of the screen SC from thestorage section 60 to compare (step S9) the threshold value with thedistance between the coordinates calculated in the step S4. Thethreshold value for the lower part is set to a higher value than thethreshold value for the upper part. In the case in which the distancebetween the coordinates is shorter than the threshold value for thelower part (YES in the step S10), the detection control section 34changes the first coordinate to the second coordinate to treat (stepS11) the first coordinate as the same coordinate as the secondcoordinate. Specifically, the detection control section 34 determinesthat an erroneous coordinate has been detected as the pointed positiondue to the wobble of the tip portion 71 when operating the firstpointing element 70, and changes the first coordinate to the secondcoordinate. Further, in the case in which the distance between thecoordinates is equal to or longer than the threshold value for the lowerpart (NO in the step S10), the detection control section 34 determines(step S12) the distance as a movement of the coordinate. In other words,the detection control section 34 determines that the pointed position bythe first pointing element 70 has been changed from the secondcoordinate to the first coordinate.

Then, the detection control section 34 determines (step S13) whether ornot the first coordinate has newly been input. In the case in which thenew first coordinate has been input (YES in the step S13), the detectioncontrol section 34 returns to the step S2 to repeat the processes fromthe step S2 once again. Further, in the case in which the new firstcoordinate has not been input (NO in the step S13), the detectioncontrol section 34 terminates the processing flow.

Further, when the process of changing the coordinate detected from thedata of the shot image is complete, and thus, the pointed position isfixed, the detection control section 34 generates locus datarepresenting the movement locus of the pointed position based on thecoordinates consecutively input from the detection section 50. As thelocus data, the detection control section 34 generates an aggregate ofthe coordinates, which are the coordinates of the pointed positionspointed by a single pointing element 70 or 80, and at which the pointingelement 70 or 80 is determined to have contact with the screen SC.Further, as the locus data, the detection control section 34 can alsogenerate an aggregate of the coordinates, which are the coordinates ofthe pointed positions pointed by a single pointing element 70, and atwhich the pointing element 70 is determined not to have contact with thescreen SC. It is also possible for the detection control section 34 todetect, for example, a gesture with the pointing element 70 using thelocus data representing the aggregate of the coordinates at which thepointing element 70 is determined not to have contact with the screenSC.

The detection control section 34 passes the coordinate of the pointedposition, the identification information representing the fact that thepointing element having pointed the coordinate is the first pointingelement 70, and the information representing whether the tip portion 71of the first pointing element 70 and the screen SC are in the contactstate or in the non-contact state, to the processing section 35.Further, the detection control section 34 passes the coordinate of thepointed position and the identification information representing thefact that the pointing element having pointed the coordinate is thesecond pointing element 80, to the processing section 35. Further, thedetection control section 34 passes the locus data, and theidentification information of the pointing element 70 or 80 havingpointed the locus data, to the processing section 35.

The processing section 35 performs a predetermined process based on thecoordinate of the pointed position or the locus data obtained from thedetection control section 34. The processing section 35 performs, forexample, the function assigned to a button in the menu bar overlappingthe coordinate of the pointed position thus obtained. The menu bar is anobject showing a list of the selectable functions on the screen SC, andas the selectable functions, there can be cited, for example, drawing ofa figure (e.g., a curved line, a straight line, a circle, an ellipse, ora quadrangle), coloring of the figure having been drawn, partial erasureof the figure having been drawn, and undoing of a process. Further, theprocessing section 35 performs a process of, for example, making theimage processing section 40 draw a figure, characters, and symbols basedon the locus data, then superimpose the figure and so on thus drawn onthe input image input through the image T/F section 12, and then projectthe result.

Further, it is also possible for the processing section 35 to output thecoordinate thus obtained to an external device such as a PC connected tothe I/F section 11. In this case, it is also possible for the processingsection 35 to convert the coordinate thus obtained into a data formatwhich can be recognized as an input of a coordinate input device in theoperating system of the external device connected to the I/F section 11,and then output the result. For example, in the case in which the PCoperating with the Windows (registered trademark) operating system isconnected to the I/F section 11, the processing section 35 outputs thedata to be processed as the input data of the HID (human interfacedevice) in the operating system.

Second Embodiment

In the present embodiment, the coordinate of the pointed positionpointed by the second pointing element 80 is corrected. It should benoted that the configuration of the projector 10, the light emittingdevice 100, and the first pointing element 70 is the same as that of thefirst embodiment shown in FIG. 2, and therefore, the description thereofwill be omitted.

FIG. 5 is a diagram showing a state of detecting a pointed position bythe second pointing element 80.

In the case of detecting the pointed position by the second pointingelement 80, the reflected light of the infrared light L reflected by thesecond pointing element 80 is detected. Specifically, the image of thereflected light of the infrared light L is detected from the data of theshot image shot from the shooting direction PA. The emission directionof the infrared light L is roughly parallel to the screen SC, and theinfrared light L is distant from the screen SC as much as apredetermined distance (hereinafter referred to as a distance G).Although the distance G varies in accordance with the attaching positionof the light emitting device 100 to the screen SC, it is structurallydifficult to reduce the distance G to zero. Therefore, in the data ofthe shot image shot from the shooting direction PA, there appears theimage of the reflected light reflected at a reflection position 80 adistant from the screen SC as much as the distance G on the tip of thesecond pointing element 80. The reflection position 80 a is detected asa position 80 b distant from the shooting section 51 in the shootingdirection PA, and causes an error of a distance D1.

FIG. 6 is a diagram showing a state of detecting the pointed position bythe second pointing element 80. The detection error of the pointedposition caused in the case in which the infrared light L emitted fromthe light emitting device 100 is not parallel to the screen SC will bedescribed.

In the case in which the screen SC is disposed oblique to the verticaldirection, or in the case in which the light emitting device 100 isinstalled at a tilt, the infrared light L is emitted nonparallel to thescreen SC in some cases. It is preferable for the infrared light L to beadjusted to be parallel to the screen SC, or in a manner that the longerthe distance from the light emitting device 100 is, the shorter thedistance between the infrared light L and the screen SC is. However,since the infrared light L is invisible, the infrared light L is notnecessarily parallel to the screen SC in some cases.

FIG. 6 shows infrared light emitted from the light emitting device 100and nonparallel to the screen SC as infrared light L1. Further, for thesake of comparison, infrared light emitted from the light emittingdevice 100 and parallel to the screen SC is shown as infrared light L2.The infrared light L1 increases in distance from the screen SC as thedistance from the light emitting device 100 increases. In the presentembodiment, since the light emitting device 100 is installed in the toppart of the screen SC, the lower the position on the screen SC is, thelonger the distance between the infrared light L2 and the screen SC is.

If the infrared light L emitted from the light emitting device 100 asthe detection light is not parallel to the screen SC, it results thatthe error in pointed position by the second pointing element 80 detectedfrom the data of the shot image differs depending on the position in thescreen SC. For example, in FIG. 6, in the case in which the position 80c on the screen SC is pointed by the second pointing element 80, and theimage of the reflected light of the infrared light L1 is shot by theshooting section 51, the reflection position is detected in the shootingdirection PA as the position 80 e. Further, in the case in which theposition 80 c on the screen SC is pointed by the second pointing element80, and the image of the reflected light of the infrared light L2 isshot by the shooting section 51, the reflection position is detected inthe shooting direction PA as the position 80 d. Therefore, the error D2shown in FIG. 6 is caused depending on whether the infrared light usedfor the detection of the pointed position is the infrared light L1 orthe infrared light L2.

Further, in FIG. 6, in the case in which the position 80 f on the screenSC is pointed by the second pointing element 80, and the image of thereflected light of the infrared light L1 is shot by the shooting section51, the reflection position is detected in the shooting direction PA asthe position 80 h. Further, in the case in which the position 80 f onthe screen SC is pointed by the second pointing element 80, and theimage of the reflected light of the infrared light L2 is shot by theshooting section 51, the reflection position is detected in the shootingdirection PA as the position 80 g. Therefore, the error D3 shown in FIG.6 is caused depending on whether the infrared light used for thedetection of the pointed position is the infrared light L1 or theinfrared light L2. Further, the error D3 is larger than the error D2.Therefore, the further the pointed position by the second pointingelement 80 is located from the shooting section 51 (the lower thepointed position on the screen SC is located), the larger the error inposition detection becomes.

The detection control section 34 according to the present embodimentdetermines whether the third coordinate, which is obtained by convertingthe first coordinate pointed by the second pointing element 80 into thecoordinate on the screen SC, is a coordinate included in the upper partof the screen SC, or a coordinate included in the lower part thereof.

In the case in which the detection control section 34 has determinedthat the third coordinate is the coordinate included in the upper partof the screen SC, the detection control section 34 does not perform anyprocesses. In other words, the detection control section 34 does notperform the process of treating the first coordinate as the samecoordinate as the second coordinate described above.

Further, if the detection control section 34 has determined that thethird coordinate is the coordinate included in the lower part of thescreen SC, the detection control section 34 compares the distancebetween the coordinates, namely the first coordinate and the secondcoordinate, and the threshold value with each other as described aboveto determine whether or not the first coordinate will be changed to thesecond coordinate. In the case in which the distance between thecoordinates is shorter than the threshold value, the detection controlsection 34 changes the first coordinate to the second coordinate totreat the first coordinate as the same coordinate as the secondcoordinate. Further, in the case in which the distance between thecoordinates is equal to or longer than the threshold value, thedetection control section 34 determines that a movement of thecoordinate has occurred, and then determines that the pointed positionby the second pointing element 80 has been changed from the secondcoordinate to the first coordinate.

Further, the detection control section 34 changes the threshold valueused in the comparison with the distance between the coordinates inaccordance with the distance from the shooting section 51 to the firstcoordinate, or to the third coordinate. As described with reference toFIG. 6, the further the pointed position on the screen SC is locatedfrom the shooting section 51, the larger the error value becomes.Therefore, the threshold value is set so that the longer the distancefrom the shooting section 51 becomes, the higher the threshold valuebecomes. In other words, a range set in the first position of the screenSC is set so as to be larger than a range set in the second positioncloser to the shooting section 51 than the first position. For example,in the case of the configuration in which the shooting section 51 isinstalled in the top part of the screen SC, it is also possible to adoptthe value, which is obtained by multiplying the distance from the toppart of the screen SC to the first coordinate or the third coordinate bya basic threshold value, as the threshold value used for the comparisonwith the distance between the coordinates. The basic threshold value isa threshold value generated and then stored in the storage section 60 inadvance.

Further, it is also possible to obtain the threshold value used for thecomparison with the distance between the coordinates by multiplying thedistance from the shooting section 51 to the first coordinate or thethird coordinate by the basic threshold value. In this case, forexample, it is necessary for the operator to operate the operation panel17 to set the distance from the shooting section 51 to the upper end ofthe screen SC to store the distance in the storage section 60 inadvance.

Although in the explanation described above, it is assumed that noprocess is performed in the case in which the third coordinate is thecoordinate included in the upper part of the screen SC, it is alsopossible to compare the distance between the coordinates with thethreshold value to determine whether or not the first coordinate istreated as the same coordinate as the second coordinate even in the casein which the third coordinate is the coordinate included in the upperpart of the screen SC. Regarding the threshold value used in this case,it is preferable to use the value, which is obtained by multiplying thedistance from the top part of the screen SC to the first coordinate orthe third coordinate by the basic threshold value, as the thresholdvalue.

As described hereinabove, the position detection device 65 of the firstand second embodiments to which the invention is applied is providedwith the detection section 50 and the control section 30. The detectionsection 50 detects an operation to the screen SC. The control section 30identifies the pointing element 70, 80 with which the operation detectedby the detection section 50 is performed, and then associates theoperation and the pointing element 70, 80 with each other. Further, thecontrol section 30 processes the operation associated with the pointingelement 70, 80 out of the operations detected by the detection section50.

Further, in the case in which a first operation and a second operation,which is performed within a predetermined period of time before thefirst operation, with a single pointing element are detected, and acoordinate of the first operation and a coordinate of the secondoperation are located within a predetermined range, the control section30 treats the coordinate of the first operation as the same coordinateas the coordinate of the second operation. Further, the control section30 changes the predetermined range in accordance with the detectionposition in the screen SC of the operation detected by the detectionsection 50. Therefore, it is possible to improve the operability of theoperation with the pointing element 70, 80.

Further, the control section 30 determines whether or not the coordinateof the first operation is determined as the same coordinate as thecoordinate of the second operation, in accordance with the configurationinformation 61 set so that the lower the position in the screen SC islocated, the larger the predetermined range is. Therefore, in the lowerpart of the screen SC, it is possible to increase the possibility thatthe coordinates pointed with the pointing element 70, 80 are determinedas the same coordinate despite the variation.

Further, the control section 30 determines whether or not the coordinateof the first operation is determined as the same coordinate as thecoordinate of the second operation, in accordance with the configurationinformation 61 set so that the longer the distance from the detectionsection 50 is, the larger the predetermined range is. Therefore, even inthe case in which the positions distant from the detection section 50are pointed with the pointing element 70, 80, and there is a variationin the coordinates thus pointed, it is possible to increase thepossibility that the coordinates are determined as the same coordinate.

It should be noted that the embodiments and the modified examplesdescribed above are nothing more than an example of a specific aspect towhich the invention is applied, and therefore, do not limit theinvention. Therefore, it is also possible to implement the invention asa different aspect. For example, the pointing element 70 is not limitedto the pointing element 70 having the pen-like shape, but it is alsopossible to use a laser pointer, a pointer rod, and so on.

Further, although in the embodiments described above, it is assumed thatthe detection section 50 shoots the screen SC with the shooting section51 to identify the position of the pointing element 70, the invention isnot limited to this configuration. For example, the shooting section 51is not limited to a device provided to the main body of the projector 10and shooting the projection direction of the projection optical system23. It is also possible to configure the position detection device usingthe shooting section 51 separated from the main body of the projector10, and to arrange that the shooting section 51 performs shooting fromthe side or the front of the screen SC. Further, it is also possible todispose a plurality of shooting sections 51 to detect the position ofthe pointing element 70 by the detection section 50 based on the data ofthe shot images by the plurality of shooting sections 51. Further, thefunctions of the detection control section 34 and the processing section35 of the control section 30 can be realized as a position detectiondevice independent of the projector 10. Further, there can also berealized a configuration in which a display device other than theprojector is provided with the functions of the detection section 50,and the detection control section 34 and the processing section 35 ofthe control section 30 to operate the display device as the positiondetection device.

Further, although in the above description of the embodiments, there isdescribed the configuration in which the signal for synchronization istransmitted from the projector 10 to the pointing element 70 using theinfrared signal emitted by the transmitting section 53, the signal forsynchronization is not limited to the infrared signal. For example, itis possible to adopt a configuration of transmitting the signal forsynchronization with radio wave communication or ultrasonic wirelesscommunication. This configuration can be realized by providing thetransmitting section 53 for transmitting the signal with the radio wavecommunication or the ultrasonic wireless communication to the projector10, and providing the similar receiving section to the pointing element70.

Further, although in the above description of the embodiments, there isdescribed the example of determining whether or not the tip portion 71of the pointing element 70 is pressed against the screen SC based on thelighting pattern of the transmitting/receiving section 74, the inventionis not limited to this example. For example, whether or not the tipportion 71 of the pointing element 70 is pressed against the screen SCcan also be determined by detecting the image of the pointing element 70and the image of a shadow of the pointing element 70 from the data ofthe shot image.

Further, although in the above description of the embodiments, theexplanation is presented citing the configuration, in which the threetransmissive liquid crystal panels corresponding respectively to thecolors of R, G, and B are used as the light modulation device 22 formodulating the light emitted by the light source, as an example, theinvention is not limited to this example. For example, it is alsopossible to adopt a configuration of using three reflective liquidcrystal panels, or to use a system having a liquid crystal panel and acolor wheel combined with each other. Further, the invention can beconstituted by a system using three digital mirror devices (DMD), a DMDsystem having a single digital mirror device and a color wheel combinedwith each other, or the like. In the case of using just one liquidcrystal panel or DMD as the light modulation device, the membercorresponding to the combining optical system such as the cross dichroicprism is unnecessary. Further, besides the liquid crystal panel or theDMD, any light modulation devices capable of modulating the lightemitted by the light source can be adopted without problems.

Further, each of the functional sections of the projector 10 shown inFIG. 2 is for showing the functional configuration, and the specificmounting forms are not particularly limited. In other words, it is notnecessarily required to install the hardware corresponding individuallyto each of the functional sections, but it is obviously possible toadopt the configuration of realizing the functions of the plurality offunctional sections by a single processor executing a program. Further,a part of the function realized by software in the embodiments describedabove can also be realized by hardware, or a part of the functionrealized by hardware can also be realized by software. Besides theabove, the specific detailed configuration of each of other sections ofthe projector 10 can arbitrarily be modified within the scope or thespirit of the invention.

What is claimed is:
 1. A position detection device comprising: adetection section adapted to detect an operation to a display surface;an identification section adapted to identify a pointing element withwhich the operation detected by the detection section is performed, andassociate the operation and the pointing element with each other; and aprocessing section adapted to process the operation associated with thepointing element out of the operations detected by the detectionsection, wherein, in a case in which a first operation and a secondoperation, which is performed within a predetermined period of timebefore the first operation, with a single pointing element are detected,and a coordinate of the first operation and a coordinate of the secondoperation are located within a predetermined range, the identificationsection treats the coordinate of the first operation as the samecoordinate as the coordinate of the second operation, and theidentification section changes a predetermined range in accordance witha detection position in the display surface of the operation detected bythe detection section.
 2. The position detection device according toclaim 1, wherein the identification section determines whether or notthe coordinate of the first operation is treated as the same coordinateas the coordinate of the second operation in accordance withconfiguration information set so that the range set to a first positionin the display surface is larger than the range set to a second positionlocated above the first position.
 3. The position detection deviceaccording to claim 1, wherein the identification section determineswhether or not the coordinate of the first operation is treated as thesame coordinate as the coordinate of the second operation in accordancewith configuration information set so that the range set to a firstposition in the display surface is larger than the range set to a secondposition located closer to the detection section than the firstposition.
 4. The position detection device according to claim 3, furthercomprising: an emission section installed in a top part of the displaysurface, and adapted to emit detection light used to detect the pointingelement, wherein the detection section is installed in the top part ofthe display surface, and shoots the detection light reflected by thepointing element, with which the operation to the display surface isperformed, to detect the operation to the display surface with thepointing element.
 5. A display device comprising: a display sectionadapted to display an image on a display surface; a detection sectionadapted to detect an operation to the display surface; an identificationsection adapted to identify a pointing element with which the operationdetected by the detection section is performed, and associate theoperation and the pointing element with each other; and a processingsection adapted to process the operation associated with the pointingelement out of the operations detected by the detection section,wherein, in a case in which a first operation and a second operation,which is performed within a predetermined period of time before thefirst operation, with a single pointing element are detected, and acoordinate of the first operation and a coordinate of the secondoperation are located within a predetermined range, the identificationsection treats the coordinate of the first operation as the samecoordinate as the coordinate of the second operation, and theidentification section changes a predetermined range in accordance witha detection position in the display surface of the operation detected bythe detection section.
 6. A method of controlling a position detectiondevice, comprising: detecting an operation to a display surface;identifying a pointing element with which the operation detected in thedetecting is performed, and associating the operation and the pointingelement with each other; and processing the operation associated withthe pointing element out of the operations detected in the detecting,wherein, in a case in which a first operation and a second operation,which is performed within a predetermined period of time before thefirst operation, with a single pointing element are detected, and acoordinate of the first operation and a coordinate of the secondoperation are located within a predetermined range, the coordinate ofthe first operation is treated as the same coordinate as the coordinateof the second operation in the associating, and a predetermined range ischanged in accordance with a detection position in the display surfaceof the operation detected in the detecting.